Re: [Paddlewise] Stability & comfort - was Evolution Kayaks

Peter,
  Primary stability has almost nothing to do with the cross sectional  
shape of a boat. Chines, no chines, makes no difference. It is the  
shape of the water plane and the height of the center of gravity that  
will determine initial stability.
  Secondary stability starts to have some relation to hull shape, but  
what matters as much as anything is the volume of the boat above the  
level waterline which begins to get submerged as you lean or tip the  
boat. For more discussion on the subject I have an article on my  
website: http://www.guillemot-kayaks.com/Design/StabilityArticle.html
Nick

On May 10, 2005, at 9:15 AM, PeterO wrote:

> G'Day Dave, John and Paddlewise,
>
> As a follow on, thought I'ld test my assumed knowledge in case its  
> wrong.
> Here's an approximation, not to scale, of a chined boat cross  
> section with
> letters at the corners for reference.
>
>
>                Boat X section
>      A                                 E
>       #                               #
>        #                             #
>         B                           D
>               #               #
>   ....................C......................X
>
> If the section CD is aligned with the wave surface, is it the  
> design aim,
> for a chined boat that this is nearly the point of initial (primary)
> stability. Would the point of secondary stability be when section  
> CDE is
> roughly aligned with the wave surface. Clearly this is an over
> simplification depending on the centre of gravity of the boat and  
> its load,
> but the presence of such well defined planes in this style of boat  
> suggests
> that its not a bad approximation.
>
> If the assumptions are correct then wouldn't chined boats have to  
> be edged
> beyond their point of initial (primary) stability to remain  
> vertical in a
> choppy sea where the wave face is at a greater angle than XCD?
***************************************************************************
PaddleWise Paddling Mailing List - Any opinions or suggestions expressed
here are solely those of the writer(s). You must assume the entire
responsibility for reliance upon them. All postings copyright the author.
Submissions:     PaddleWise_at_PaddleWise.net
Subscriptions:   PaddleWise-request_at_PaddleWise.net
Website:         http://www.paddlewise.net/
***************************************************************************